The vessel dropped about one kilometre off the US West Coast was named after a Leona Philpot character in popular Xbox video game franchise, Halo.

Microsoft said with about half of the world's population living near large bodies of water and a shift to accessing software hosted in the internet cloud, nearby submerged data centres could save money and speed up access to information.

Currents or tides could be tapped to generate electricity to power data centres, and the cold depths would provide natural cooling.

"The bottom line is that in one day this thing was deployed, hooked up and running," Microsoft Research NExT special projects leader, Norm Whitaker, said in a post at the company's website.

After each five-year deployment cycle, the data centre would be retrieved, reloaded with new computers, and redeployed. The target lifespan of a Natick data centre is at least 20 years. After that, the data centre is designed to be retrieved and recycled.

Microsoft last week reported earnings that surpassed Wall Street expectations with a winning shift into the internet cloud.

Microsoft made a profit of $5 billion on $23.8 billion in revenue in the final three months of last year.

Software offered as a service in the internet cloud has been a key aspect of Microsoft's effort to adapt to a shift away from packaged software on which the US company was built.